A method for resource utilization of waste denitration catalyst and a regenerated activation impregnation solution

Abstract

The application belongs to the field of resource utilization of waste denitration catalyst, and discloses a method for resource utilization of waste denitration catalyst and a regenerated activation impregnation solution. The method can effectively recover most of the elements in the waste denitration catalyst, and through multi-stage processing, two regenerated products, black titanium dioxide and the regenerated activation impregnation solution, are obtained, thereby reducing resource waste and improving the recycling efficiency. The regenerated activation impregnation solution prepared by the method contains active supplement components and structural reinforcement components at the same time, and when used for regenerating the denitration catalyst, the regenerated activation impregnation solution can supplement the activity and structural strength of the catalyst at the same time, thereby prolonging the service life of the regenerated denitration catalyst.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of resource utilization of waste denitration catalysts, and particularly relates to a method for resource utilization of waste denitration catalysts and a regenerated activation impregnation solution. BACKGROUND

[0002] The selective catalytic reduction (SCR) denitration technology is the most mature flue gas denitration technology at present. As the core of the SCR denitration technology, the SCR denitration catalyst will be deactivated due to ash accumulation, blockage, wear, sintering, chemical poisoning, and loss of active components, etc. during use. The denitration catalyst that has reached the end of its service life is called a waste denitration catalyst, and its harmless disposal and resource utilization have become a difficult problem for fossil fuel using enterprises such as coal-fired power plants. Since the waste denitration catalyst contains valuable metals such as vanadium, tungsten, molybdenum, and titanium, if not properly disposed of, it will cause serious environmental pollution and resource waste.

[0003] At present, the resource utilization method of the waste denitration catalyst mainly adopts the sodiumization roasting method, and the active components are recovered by solution leaching by changing the state of vanadium, tungsten, and molybdenum in the catalyst as active components. Generally, the recovered active components will be further processed to prepare a regenerated activation impregnation solution for the denitration catalyst. However, this method mainly recovers the active components with a low content in the waste denitration catalyst, and has a low recovery and utilization rate of elements such as silicon, aluminum, and titanium, which constitute the main part of the waste denitration catalyst, resulting in a large resource waste. The regenerated activation impregnation solution obtained by this method only contains vanadium, tungsten, molybdenum, and other components for supplementing the activity, and cannot realize the reinforcement of the structure of the denitration catalyst, so that the structural strength of the regenerated denitration catalyst is reduced and the service life is reduced. This method needs to use a large amount of sodium-containing salt or alkali, introduces sodium ions which are not conducive to the catalytic activity of the denitration catalyst, and the recovered active components often need to remove sodium elements to be used for preparing the regenerated activation impregnation solution. Black titanium dioxide is one of the catalytic materials that have been studied more in recent years, and has a wide application prospect in the fields of photocatalysis, electrocatalysis, photoelectrocatalysis, and thermal catalysis. Since the black titanium dioxide usually needs to use white titanium dioxide as a raw material and is prepared by methods such as hydrogenation, chemical reduction, chemical oxidation, hydrogen plasma, electrochemical reduction, and laser ablation. Therefore, the conventional black titanium dioxide preparation method has the problem of high production cost, and it is urgent to select a suitable raw material to reduce the production cost. SUMMARY

[0004] The application aims to overcome the problems of low resource recycling efficiency of waste denitration catalyst and poor regeneration effect of regenerated activation impregnation solution in the prior art, and provides a resource utilization method of waste denitration catalyst and a regenerated activation impregnation solution. The method can fully recycle most components of the waste denitration catalyst, and effectively improves the resource utilization rate of the waste denitration catalyst by preparing black titanium dioxide and the regenerated activation impregnation solution through systematic multi-stage processing. The regenerated activation impregnation solution prepared by the method not only contains active supplement components, but also contains structure reinforcing components, and has better regeneration effect.

[0005] In one aspect, the application provides a resource utilization method of waste denitration catalyst, which comprises the following steps:

[0006] (1) sequentially blowing and flushing the waste denitration catalyst module, then unpacking, crushing and grinding the cleaned waste denitration catalyst into a powder with a particle size of 100-400 mesh;

[0007] (2) performing first-stage acid washing on the ground powder using a first acid solution, and then performing first-stage solid-liquid separation on the acid-washed slurry;

[0008] (3) performing second-stage acid washing on the solid obtained by the first-stage solid-liquid separation using a second acid solution, and then performing second-stage solid-liquid separation on the acid-washed slurry;

[0009] (4) cleaning and drying the solid obtained by the second-stage solid-liquid separation, and performing thermal reduction treatment on the obtained gray powder to obtain black titanium dioxide;

[0010] (5) adding an organic non-metallic strong base to the liquid obtained by the second-stage solid-liquid separation, adjusting the pH value to alkaline, and then performing constant temperature treatment, and then removing the precipitate by filtration to obtain a regenerated activation impregnation solution;

[0011] Preferably, the first acid solution contains at least one of hydrochloric acid, nitric acid and sulfuric acid.

[0012] Preferably, the first acid solution further contains an oxidizing agent. More preferably, the oxidizing agent is at least one of hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium persulfate.

[0013] Preferably, the second acid solution is at least one of oxalic acid, tartaric acid and citric acid.

[0014] Preferably, in step (3), the conditions of the second-stage acid washing include a temperature of 30-90℃ and a time of 1-4h.

[0015] Preferably, in step (3), the conditions of the second-stage acid washing include a temperature of 30-90℃ and a time of 1-4h.

[0016] Preferably, in step (4), the thermal reduction treatment comprises: heating and reducing the gray powder in a reducing atmosphere, and then naturally cooling.

[0017] Preferably, the condition of the thermal reduction treatment is: reducing reaction at 280-320℃ for 1-5h.

[0018] Preferably, the reducing atmosphere is H2 / N2 mixed gas containing 1-5% H2 by volume or CO / N2 mixed gas containing 1-5% CO by volume.

[0019] Preferably, the organic non-metallic strong base is at least one of quaternary ammonium base, choline and guanidine.

[0020] Preferably, in step (5), the condition of the constant temperature treatment is: reaction at 60-90℃ for 0.5-3h.

[0021] The condition of the constant temperature treatment is: reaction at 60-90℃ for 0.5-3h; more preferably, reaction at 65-85℃ for 1-2.5h; most preferably, reaction at 70-80℃ for 1.5-2h.

[0022] The second aspect of the present application provides a regenerated activation impregnation solution prepared by the above method, which contains active supplement components and structural reinforcement components at the same time.

[0023] Preferably, the active supplement components are at least one of vanadium, tungsten and molybdenum.

[0024] Preferably, the structural reinforcement components are at least one of silicon and aluminum.

[0025] According to the resource utilization method of the waste denitration catalyst, elements such as iron, potassium, sodium and arsenic that cause poisoning of the denitration catalyst can be effectively removed from the waste denitration catalyst, the titanium dioxide carrier in the waste denitration catalyst is converted into high-value black titanium dioxide at low cost, and vanadium, tungsten, molybdenum, silicon, aluminum and other elements are efficiently leached to prepare a regenerated activation impregnation solution, thereby improving the resource utilization efficiency of the waste denitration catalyst.

[0026] The regenerated activation impregnation solution obtained by the method contains active supplement components such as vanadium, tungsten and molybdenum and structural reinforcement components such as silicon and aluminum at the same time, so that the denitration catalyst after impregnation and regeneration obtains catalytic activity supplement and structural reinforcement, thereby improving the regeneration effect and being conducive to the continued use of the regenerated denitration catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a schematic diagram of the resource utilization method of the waste denitration catalyst of the present application. DETAILED DESCRIPTION

[0028] The specific embodiments of the present application are described in detail below. It should be understood that the detailed description and specific examples described herein are intended for purposes of illustration only and are not intended to limit the present application.

[0029] The endpoints of the ranges and any values described herein are not limited to the precise values stated. The endpoints of the ranges and values are provided as approximate descriptions of the ranges and values. Each range has a resolution between the endpoints. Each maximum value can be obtained by adding the resolution to each minimum value. Each minimum value can be obtained by subtracting the resolution from each maximum value. The resolution of each range or value should be assumed to be one unit unless otherwise stated.

[0030] The method for resource utilization of the waste denitration catalyst comprises the following steps:

[0031] (1) sequentially purging and flushing the waste denitration catalyst module, then unpacking the cleaned waste denitration catalyst, crushing and grinding into a powder with a particle size of 100-400 mesh;

[0032] (2) using a first acid solution to perform primary acid washing on the ground powder, then performing first solid-liquid separation on the acid-washed slurry;

[0033] (3) using a second acid solution to perform secondary acid washing on the solid obtained by the first solid-liquid separation, then performing second solid-liquid separation on the acid-washed slurry;

[0034] (4) cleaning and drying the solid obtained by the second solid-liquid separation, and performing thermal reduction treatment on the obtained gray powder to obtain black titanium dioxide;

[0035] (5) adding an organic non-metallic strong base to the liquid obtained by the second solid-liquid separation, adjusting the pH value to be alkaline, then performing constant temperature treatment, and removing the precipitate by filtration to obtain a regenerated activation immersion liquid;

[0036] In the method, the first acid solution contains at least one of hydrochloric acid, nitric acid and sulfuric acid. In the present application, the above-mentioned inorganic strong acid cleaning can remove alkali metals such as potassium and sodium and alkaline earth metals such as calcium which have a poisoning effect on the denitration catalyst, and remove part of the toxic and harmful iron element.

[0037] In the method, the first acid solution contains at least one of hydrochloric acid, nitric acid and sulfuric acid. In the present application, the above-mentioned inorganic strong acid cleaning can remove alkali metals such as potassium and sodium and alkaline earth metals such as calcium which have a poisoning effect on the denitration catalyst, and remove part of the toxic and harmful iron element.

[0038] In the method of the present application, preferably, the first acid solution further comprises an oxidizing agent. More preferably, the oxidizing agent is at least one of hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium persulfate. In the present application, the first acid solution containing the oxidizing agent is used for the first-stage pickling, which can effectively improve the removal rate of arsenic and deeply oxidize the residual organic matters (such as coal tar) on the surface of the catalyst.

[0039] In the method of the present application, preferably, the second acid solution is at least one of oxalic acid, tartaric acid and citric acid. In the present application, the reducing acid is used as the second acid solution, which can effectively leach vanadium, tungsten, molybdenum, silicon, aluminum and iron and other elements in the titanium dioxide carrier. These elements are partially embedded in the crystal lattice of titanium dioxide during calcination, and after leaching, Ti 3+ and oxygen vacancies and other lattice defects can be generated in the titanium dioxide, and the reducing acid can also reduce part of Ti 4+ in the titanium dioxide to Ti 3+ , so that the final solid powder is gray after water washing and drying, which is black titanium dioxide powder.

[0040] In the method of the present application, preferably, in step (3), the conditions of the second-stage pickling include a temperature of 30-90℃ and a time of 1-4h; further preferably, the reaction is carried out at 40-70℃ for 1.5-3.5h; most preferably, the reaction is carried out at 45-65℃ for 2-3h.

[0041] In the method of the present application, preferably, in step (4), the heat reduction treatment comprises heating and reducing the gray powder in a reducing atmosphere, and then naturally cooling. In the present application, the heat reduction treatment can reduce part of titanium ions in the gray powder (i.e. black titanium dioxide powder), further improve the defect degree of Ti 3+ and oxygen vacancies in the black titanium dioxide, and obtain better catalytic performance.

[0042] In the method of the present application, preferably, the conditions of the heat reduction treatment are a reduction reaction at 280-320℃ for 1-5h; more preferably, the reduction reaction is carried out at 290-310℃ for 2-4h.

[0043] Specifically, in the method of the present application, preferably, the heat reduction treatment process comprises heating the gray powder from room temperature to 280-320℃ at a heating rate of 1-3℃·min -1 in a reducing atmosphere, and then reducing for 1-5h, and then naturally cooling. More preferably, the heating rate is 1.5-2.5℃·min -1 , the temperature is 290-310℃, and the reduction reaction time is 2-4h.

[0044] In the method of the present application, preferably, the reducing atmosphere is a H2 / N2 mixed gas containing 1-5% H2 by volume or a CO / N2 mixed gas containing 1-5% CO by volume.

[0045] In the method of the present application, preferably, the organic non-metallic strong base is at least one of quaternary ammonium base, choline and guanidine. In the present application, the pH of the liquid obtained from the second solid-liquid separation is adjusted to be alkaline by using the organic non-metallic strong base, which can effectively avoid introducing Na ions harmful to the de-nitration catalyst into the final obtained reactivated impregnation liquid, ensuring the low impurity content of the reactivated impregnation liquid; at the same time, the alkaline environment provided by the organic non-metallic strong base can further remove the iron elements contained in the liquid, converting them into Fe(OH)3 precipitate and removing them by filtration.

[0046] In the method of the present application, preferably, in step (5), the constant temperature treatment is carried out at 60-90°C for 0.5-3h; more preferably, at 65-85°C for 1-2.5h; most preferably, at 70-80°C for 1.5-2h.

[0047] In a specific embodiment, as shown in Figure 1 The specific process of the preparation method can include:

[0048] (1) The waste de-nitration catalyst module is purged with compressed air at 0.3-0.7 MPa, and then washed with high-pressure water at 0.8-1.6 MPa to clean the fly ash attached to the surface and pores of the waste de-nitration catalyst, then the cleaned waste de-nitration catalyst module is unpacked, crushed by a crusher and ground into a powder with a particle size of 100-400 mesh by a ball mill. The ball mill can use ZrO2 balls and the like which do not contain iron elements to avoid introducing additional iron elements;

[0049] (2) The ground powder is subjected to primary acid pickling with a first acid liquid containing at least one of hydrochloric acid, sulfuric acid and nitric acid, and the concentration of the acid is controlled at 0.1-2 mol / L; the first acid liquid can also contain an oxidizing agent to further improve the removal rate of arsenic elements, and the oxidizing agent is at least one of hydrogen peroxide, hypochlorous acid, sodium hypochlorite and sodium persulfate, and the concentration of the oxidizing agent is generally controlled at 0.5-5 wt.%; in the process of primary acid pickling, ultrasonic waves can be used in conjunction to further improve the removal efficiency of alkali metals and alkaline earth metals such as K and Na, and the frequency of the ultrasonic waves is generally controlled at 20-80 kHz, and the acid pickling time is 10-30 min; then the slurry obtained from the primary acid pickling is subjected to first solid-liquid separation;

[0050] (3) the solid obtained from the first solid-liquid separation is subjected to secondary acid pickling using a second acid liquor, the second acid liquor is at least one of oxalic acid, tartaric acid and citric acid, the concentration of the acid is controlled to be 0.1-2 mol / L, the temperature of the secondary acid pickling is 30-90°C, and the time is 1-4 h; then the slurry obtained from the secondary acid pickling is subjected to second solid-liquid separation;

[0051] (4) the solid obtained from the second solid-liquid separation is washed with desalted water or deionized water until the conductivity of the filtrate after washing is <100 μS / cm, then the washed solid is dried at 95-120°C for 1-4 h to obtain a gray powder (i.e. black titanium dioxide coarse powder), then the gray powder is heated to 280-320°C at a heating rate of 1-3°C·min -1 in a reducing atmosphere, and then reduced for 1-5 h, and then naturally cooled to obtain black titanium dioxide, the reducing atmosphere is H2 / N2 mixed gas containing 1-5% H2 by volume or CO / N2 mixed gas containing 1-5% CO by volume;

[0052] (5) an organic non-metallic strong base is added to the liquid obtained from the second solid-liquid separation, the pH is adjusted to be alkaline, the organic non-metallic strong base is at least one of quaternary ammonium base, choline and guanidine, and the constant temperature reaction is carried out at 60-90°C for 0.5-3 h, and the precipitate (mainly Fe(OH)3) is removed by filtration to obtain a reactivated impregnation liquid.

[0053] In the present application, the waste denitration catalyst refers to a commercial SCR denitration catalyst module reaching the service life. In some embodiments, the waste denitration catalyst mainly contains a TiO2 carrier and components such as V2O5, WO3, SiO2 and Al2O3, and also contains toxic substances such as sodium, potassium, iron and arsenic that cause its waste inactivation.

[0054] The resource utilization method of the waste denitration catalyst according to the present application can effectively remove harmful element components, successfully recycle most of the elements constituting the waste denitration catalyst, avoid resource waste, and improve the resource utilization rate; through systematic multi-stage processing, black titanium dioxide and a reactivated impregnation liquid are prepared, the types of the recovered products are enriched, and the production cost is reduced.

[0055] The reactivated impregnation liquid prepared by the above method according to the present application contains active supplement components and structure reinforcing components.

[0056] Preferably, the active supplement component is at least one of vanadium, tungsten and molybdenum.

[0057] Preferably, the structure reinforcing component is at least one of silicon and aluminum.

[0058] The prepared regenerated activation impregnation solution according to the method has vanadium, tungsten, molybdenum and other active supplement components and silicon and aluminum and other structure reinforcing components, which not only improves the recycling rate of elements in the waste denitration catalyst, but also improves the structure strength of the regenerated denitration catalyst while supplementing the activity of the denitration catalyst, and is beneficial to the use of the regenerated denitration catalyst.

[0059] The resource utilization method of the waste denitration catalyst and the regenerated activation impregnation solution of the present application will be further illustrated by examples. The examples are implemented on the premise of the technical solution of the present application, and detailed implementation modes and specific operation processes are given, but the protection scope of the present application is not limited to the following examples.

[0060] In the following examples, the experimental methods are conventional methods in the art unless otherwise specified. The experimental materials used in the following examples are commercially available unless otherwise specified.

[0061] In the following examples and comparative examples, the waste denitration catalyst module used is a commercial SCR denitration catalyst module reaching the service life, which mainly contains TiO2 carrier and V2O5, WO3, SiO2 and Al2O3 components, and also contains sodium, potassium, iron and arsenic and other toxic substances leading to its waste and inactivation.

[0062] Example 1

[0063] (1) The waste denitration catalyst module is purged with compressed air at 0.5 MPa, then washed with high-pressure water at 1.2 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst, then the cleaned waste denitration catalyst module is unpacked, crushed with a jaw crusher and ground into a 400-mesh powder with a ball mill (the ball is ZrO2);

[0064] (2) The ground powder is mixed with a mixed solution of sulfuric acid and hydrogen peroxide and treated with ultrasonic waves at a frequency of 50 kHz for 30 min, the concentration of sulfuric acid in the mixed solution is 1 mol / L, and the concentration of hydrogen peroxide (calculated as H2O2) is 3 wt%, then the slurry obtained after the first acid washing is subjected to first solid-liquid separation using a plate and frame filter press;

[0065] (3) The solid obtained by the first solid-liquid separation is mixed with oxalic acid with a concentration of 2 mol / L, heated to 60°C and acid washed for 2 h, then the slurry obtained after the second acid washing is subjected to second solid-liquid separation using a plate and frame filter press;

[0066] (4) The solid obtained by the second solid-liquid separation is washed with desalted water until the conductivity of the filtrate after washing is <100 μS / cm, and then the washed solid is dried at 105°C for 2 h to obtain a gray powder. The gray powder is then heated to 320°C at a heating rate of 1.5°C·min -1 from room temperature to 320°C in a reducing atmosphere composed of a H2 / N2 mixed gas containing 5% by volume of H2, and then reduced for 3 h, followed by natural cooling to obtain black titanium dioxide T1;

[0067] (5) A quaternary ammonium base is added to the liquid obtained by the second solid-liquid separation, the pH of the liquid is adjusted to 14, and the liquid is reacted at 80°C for 2 h, and then the precipitate is removed by filtration to obtain a reactivated activation immersion liquid L1.

[0068] Example 2

[0069] (1) The waste denitration catalyst module is purged with compressed air at 0.7 MPa, and then washed with high-pressure water at 1.5 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst. Then the washed waste denitration catalyst module is unpacked, crushed by a jaw crusher, and ground into a powder of 400 mesh by a ball mill (the ball is ZrO2);

[0070] (2) The ground powder is mixed with a mixed solution of nitric acid and sodium persulfate, and treated with ultrasonic waves at a frequency of 80 kHz for 10 min. The concentration of nitric acid in the mixed solution is 1 mol / L, and the concentration of sodium persulfate is 5 wt%. Then the slurry obtained after the first acid washing is subjected to first solid-liquid separation using a plate and frame filter press;

[0071] (3) The solid obtained by the first solid-liquid separation is mixed with citric acid at a concentration of 1.5 mol / L, heated to 50°C and kept for 3 h of acid washing. Then the slurry obtained after the second acid washing is subjected to second solid-liquid separation using a plate and frame filter press;

[0072] (4) The solid obtained by the second solid-liquid separation is washed with desalted water until the conductivity of the filtrate after washing is <100 μS / cm, and then the washed solid is dried at 95°C for 4 h to obtain a gray powder. The gray powder is then heated to 290°C at a heating rate of 2°C·min -1 from room temperature to 290°C in a reducing atmosphere composed of a H2 / N2 mixed gas containing 3% by volume of H2, and then reduced for 2.5 h, followed by natural cooling to obtain black titanium dioxide T2;

[0073] (5) A quaternary ammonium base is added to the liquid obtained by the second solid-liquid separation, the pH of the liquid is adjusted to 14, and the liquid is reacted at 70°C for 3 h, and then the precipitate is removed by filtration to obtain a reactivated activation immersion liquid L2.

[0074] Example 3

[0075] (1) The waste denitration catalyst module was purged with compressed air at 0.6 MPa, and then washed with high-pressure water at 1.3 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst. Then, the cleaned waste denitration catalyst module was unpacked, crushed with a jaw crusher, and ground into a 300-mesh powder with a ball mill (the ball was Zr02);

[0076] (2) The ground powder was mixed with a mixed solution of hydrochloric acid and sodium hypochlorite, and treated with ultrasonic waves at a frequency of 60 kHz for 15 min. The concentration of hydrochloric acid in the mixed solution was 1 mol / L, and the concentration of sodium hypochlorite was 5 wt%. Then, the slurry obtained after the first acid pickling was subjected to first solid-liquid separation using a plate and frame filter press;

[0077] (3) The solid obtained by the first solid-liquid separation was mixed with tartaric acid with a concentration of 1.5 mol / L, heated to 70°C and acid pickled for 1 h. Then, the slurry obtained after the second acid pickling was subjected to second solid-liquid separation using a plate and frame filter press;

[0078] (4) The solid obtained by the second solid-liquid separation was washed with desalted water until the conductivity of the filtrate after washing was <100 μS / cm. Then, the washed solid was dried at 110°C for 1 h to obtain a gray powder. The gray powder was heated to 320°C at a heating rate of 2°C·min -1 from room temperature in a reducing atmosphere composed of 1 vol% H2 in H2 / N2 mixed gas, and then reduced for 2 h. Subsequently, the temperature was naturally lowered to obtain black titanium dioxide T3;

[0079] (5) Quaternary ammonium base was added to the liquid obtained by the second solid-liquid separation, and the pH of the liquid was adjusted to 14. The liquid was reacted at 60°C for 4 h, and then the precipitate was removed by filtration to obtain a regenerated activation immersion liquid L3.

[0080] Example 4

[0081] (1) The waste denitration catalyst module was purged with compressed air at 0.4 MPa, and then washed with high-pressure water at 1 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst. Then, the cleaned waste denitration catalyst module was unpacked, crushed with a jaw crusher, and ground into a 200-mesh powder with a ball mill (the ball was Zr02);

[0082] (2) the mixed solution prepared by mixing the ground powder with sulfuric acid and hydrogen peroxide is treated with ultrasonic waves at a frequency of 70 kHz for 10 min, the concentration of sulfuric acid in the mixed solution is 0.5 mol / L, and the concentration of hydrogen peroxide (calculated as H2O2) is 1 wt%, then the slurry obtained after the first acid pickling is subjected to first solid-liquid separation using a plate-and-frame filter press;

[0083] (3) the solid obtained from the first solid-liquid separation is mixed with oxalic acid having a concentration of 1 mol / L, heated to 50°C and kept for acid pickling for 2 h, then the slurry obtained after the second acid pickling is subjected to second solid-liquid separation using a plate-and-frame filter press;

[0084] (4) the solid obtained from the second solid-liquid separation is washed with desalted water until the conductivity of the filtrate after washing is <100 μS / cm, then the washed solid is dried at 105°C for 2 h to obtain a gray powder, then the gray powder is heated to 290°C from room temperature at a heating rate of 2°C·min -1 , in a reducing atmosphere composed of a CO / N2 mixed gas containing 1-5 vol% CO, and then subjected to reduction reaction for 2 h, followed by natural cooling to obtain black titanium dioxide T4;

[0085] (5) quaternary ammonium base is added to the liquid obtained from the second solid-liquid separation, the pH of the liquid is adjusted to 14, and the liquid is kept at 70°C for 2 h for reaction, then the precipitate is removed by filtration to obtain a regenerated activation immersion liquid L4.

[0086] Example 5

[0087] (1) the waste denitration catalyst module is blown with compressed air at a pressure of 0.3 MPa, then washed with high-pressure water at a pressure of 0.8 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst, then the washed waste denitration catalyst module is unpacked, crushed with a jaw crusher and ground into a powder with a particle size of 100 mesh using a ball mill (the ball is ZrO2);

[0088] (2) the mixed solution prepared by mixing the ground powder with hydrochloric acid, sulfuric acid and hypochlorous acid is treated with ultrasonic waves at a frequency of 50 kHz for 10 min, the total concentration of hydrochloric acid and sulfuric acid in the mixed solution is 1 mol / L (wherein the molar ratio of hydrochloric acid to sulfuric acid is 1:1), and the concentration of hypochlorous acid (calculated as HClO) is 3 wt%, then the slurry obtained after the first acid pickling is subjected to first solid-liquid separation using a plate-and-frame filter press;

[0089] (3) the solid obtained from the first solid-liquid separation is mixed with a mixed acid solution composed of tartaric acid and citric acid (wherein the molar ratio of tartaric acid to citric acid is 1:1) having a total acid concentration of 1 mol / L, heated to 40°C and kept for acid pickling for 1 h, then the slurry obtained after the second acid pickling is subjected to second solid-liquid separation using a plate-and-frame filter press;

[0090] (4) The solid obtained from the second solid-liquid separation is washed with desalted water until the conductivity of the filtrate after washing is <100 μS / cm, and then the washed solid is dried at 100°C for 3 h to obtain a gray powder. The gray powder is then heated to 280°C at a heating rate of 3°C·min -1 from room temperature to 280°C in a reducing atmosphere composed of a CO / N2 mixed gas containing 3 vol% CO, and then reduced for 2 h, followed by natural cooling, to obtain black titanium dioxide T5;

[0091] (5) Quaternary ammonium base is added to the liquid obtained from the second solid-liquid separation, and the pH of the liquid is adjusted to 14. The liquid is then reacted at 60°C for 2 h, and then the precipitate is removed by filtration to obtain a regenerated activation immersion liquid L5.

[0092] Comparative Example 1

[0093] (1) The waste denitration catalyst module is purged with compressed air at 0.5 MPa, and then washed with high-pressure water at 1.2 MPa to clean the fly ash attached to the surface and pores of the waste denitration catalyst. The washed waste denitration catalyst module is then unpacked, crushed with a jaw crusher, and ground into a powder with a particle size of 400 mesh using a ball mill (the balls are ZrO2);

[0094] (2) The ground powder is mixed with a mixed solution of sulfuric acid and hydrogen peroxide, and treated with ultrasonic waves at a frequency of 50 kHz for 30 min. The concentration of sulfuric acid in the mixed solution is 1 mol / L, and the concentration of hydrogen peroxide (calculated as H2O2) is 3 wt%. The slurry obtained after the first acid washing is then subjected to a first solid-liquid separation using a plate-and-frame filter press;

[0095] (3) The solid obtained from the first solid-liquid separation is mixed with nitric acid at a concentration of 2 mol / L, heated to 60°C, and maintained for 2 h of acid washing. The slurry obtained after the second acid washing is then subjected to a second solid-liquid separation using a plate-and-frame filter press;

[0096] (4) The solid obtained from the second solid-liquid separation is washed with desalted water until the conductivity of the filtrate after washing is <100 μS / cm, and then the washed solid is dried at 105°C for 2 h to obtain a gray powder. The gray powder is then heated to 320°C at a heating rate of 1.5°C·min -1 from room temperature in a reducing atmosphere composed of a H2 / N2 mixed gas containing 1 vol% H2, and then reduced for 3 h, followed by natural cooling, to obtain black titanium dioxide DT1;

[0097] (5) Add quaternary ammonium base to the liquid obtained from the second solid-liquid separation, adjust the pH of the liquid to 14, and react at 80°C for 2 hours. Then filter to remove the precipitate and obtain the regenerated and activated impregnation solution DL1.

[0098] Test Example 1

[0099] X-ray photoelectron spectroscopy (XPS) was used to analyze the Ti content in the black titanium dioxide T1-T5 and DT1 obtained in Examples 1-5 and Comparative Example 1. 3+ The proportions were determined; and the denitrification reactivity of T1-T5 and DT1 powders was tested (flue gas temperature: 380℃, powder mass: 0.2g, flue gas flow rate: 1L / min, flue gas composition: 180ppm NO, 180ppm NH3, 2 vol.% O2, 10 vol.% H2O, the remainder being N2), and the results are shown in Table 1:

[0100] Table 1

[0101]

[0102] Therefore, it can be seen that the black titanium dioxide prepared by secondary acid washing with reducing acid according to the method of the present invention has more Ti content compared with titanium dioxide prepared using non-reducing acid. 3+ The content is reduced, and therefore exhibits significantly better denitrification catalytic performance, indicating that secondary acid washing with reducing acid helps to generate black titanium dioxide.

[0103] The elemental types and contents in the regenerated and activated impregnating solutions L1-L5 and DL1 obtained in Examples 1-5 and Comparative Example 1 were determined by inductively coupled plasma atomic emission spectrometry (ICP). The results are shown in Table 2.

[0104] Table 2

[0105]

[0106] Therefore, the regenerated and activated impregnating solution prepared according to the method of the present invention not only contains active supplementary components, but also contains a large amount of structural reinforcing components such as silicon and aluminum. This indicates that the method of the present invention can effectively recover structural elements such as silicon and aluminum from waste denitrification catalysts and improve resource recovery efficiency.

[0107] The deactivated denitration catalyst was regenerated using regeneration and activation impregnation solutions L1-L5 and DL1. Subsequently, the axial and radial compressive strength of the regenerated catalyst was measured according to the "Technical Specification for Testing Flue Gas Denitration Catalysts (GB / T 38219-2019)". The results are shown in Table 3.

[0108] Table 3

[0109]

[0110] Therefore, the regenerated activation impregnation solution prepared by the method has structural reinforcing components such as silicon and aluminum, and the denitration catalyst after regeneration has obviously higher structural strength, which is beneficial to the continuous use of the regenerated denitration catalyst, and shows that the regenerated activation impregnation solution has better regeneration effect compared with the regenerated activation impregnation solution without structural reinforcing components.

[0111] The above merely provides the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for the resource utilization of spent denitrification catalyst, characterized in that, The method includes the following steps: (1) The waste denitrification catalyst module is purged and rinsed in sequence, and then the cleaned waste denitrification catalyst is unpacked, crushed and ground into 100-400 mesh powder; (2) The ground powder is subjected to primary acid washing with the first acid solution, and then the slurry after acid washing is subjected to primary solid-liquid separation; (3) The solid obtained from the first solid-liquid separation is subjected to secondary acid washing with the second acid solution, and then the slurry after acid washing is subjected to a second solid-liquid separation; (4) The solid obtained from the second solid-liquid separation is washed and dried, and the resulting gray powder is subjected to thermal reduction treatment to obtain black titanium dioxide; (5) Add an organic non-metallic strong base to the liquid obtained from the second solid-liquid separation, adjust the pH value to alkaline, then treat at a constant temperature, and after filtering to remove the precipitate, the liquid obtained is a regenerated and activated impregnation solution. The first acid solution contains an inorganic strong acid and an oxidizing agent. The inorganic strong acid is at least one of hydrochloric acid, nitric acid, and sulfuric acid. The oxidizing agent is at least one of hydrogen peroxide, hypochlorous acid, sodium hypochlorite, and sodium persulfate. The second acid solution contains at least one of oxalic acid, tartaric acid, and citric acid. The organic non-metallic strong base is at least one of quaternary ammonium base, choline, and guanidine. The thermal reduction treatment is carried out in a reducing atmosphere, which is either an H2 / N2 mixture containing 1-5 vol% H2 or a CO / N2 mixture containing 1-5 vol% CO. The regeneration and activation impregnation solution contains both an active supplementary component and a structural reinforcing component. The active supplementary component is at least one of vanadium, tungsten, and molybdenum. The structural reinforcing component is at least one of silicon and aluminum.

2. The method according to claim 1, characterized in that, In step (3), the conditions for the secondary pickling include: a temperature of 30-90℃ and a time of 1-4h.

3. The method according to claim 1 or 2, characterized in that, In step (4), the thermal reduction process includes: heating and reducing the gray powder in a reducing atmosphere, and then cooling it naturally.

4. The method according to claim 3, characterized in that, The conditions for the thermal reduction treatment include: a reduction reaction at 280-320℃ for 1-5 hours.

5. The method according to claim 1, characterized in that, In step (5), the conditions for the isothermal treatment are: reaction at 60-90℃ for 0.5-3h.

6. The regenerated and activated impregnation solution prepared by the method according to any one of claims 1-5.

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